Re: [patch] Prevent -fprofile-arcs and -fbranch-probabilities rtlfrom diverging

[Nathan Sidwell <nathan at codesourcery dot com>]

Zdenek Dvorak wrote:

> > Hmm, it's not immediately obvious to me as to why inserting the
> > gcov_flush call causes the bb graph to change.
>
>
> because the optimizations before the profiling now work on different
> code, and thus behave slightly differently; I did not hunt the change
> down to one particular optimization (mostly because it would be a clear
> waste of the time -- there is nothing wrong with the optimization and
> avoiding this behavior is not a correct way of fixing the problem).
I do not understand what you are saying here.

Do you have a test case?

nathan
--
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk